1. Field of the Invention
The present invention relates to a self-compensating dynamic balancer, and more particularly, to a self-compensating dynamic balancer which restricts vibrations of moving members by regulating movements of the moving members when a main body does not rotate or rotates at a low speed below the natural frequency.
2. Description of the Related Art
In general, a disk player records/reproduces information on/from an optical disk in a non-contact method. In the disk player, as the rotational speed of a spindle motor installed therein increases, internal vibrations may be generated. The internal vibrations are generated mainly due to the revolution of the rotation center of a rotating body, that is, whirling, which is caused by disparity between the rotation center and the center of mass of the rotating body. The eccentric mass of the rotating body is produced by an error in a manufacturing process of the rotating body such as a disk. Thus, a self-compensating dynamic balancer is adopted to reduce the internal vibrations.
FIG. 1 shows the structure of the conventional self-compensating dynamic balancer. Referring to the drawing, the conventional self-compensating dynamic balancer is installed at the bottom of a turntable 1 having a guide protrusion 1a. The guide protrusion 1a guides a disk (not shown) being placed onto the turntable 1 to an appropriate position. The self-compensating dynamic balancer includes a main body 3 in which a race 4 is formed, a magnet 6 coupled along the inner circumferential surface of the race 4, a plurality of moving members 5 placed in the race 4, and a cover member 7 coupled to the main body 3 from the top. Coupling holes 1b, 7a, and 3a into which a rotation shaft 9a of the spindle motor 9 inserts are formed at the centers of the turntable 1, the cover member 7, and the main body 3, respectively. Thus, the turntable 1 and the self-compensating dynamic balancer are rotated by a rotational force provided by the spindle motor 9.
The moving members 5 are magnetized balls such that, when the spindle motor 9 does not rotate or rotates at a low speed, they stick to the magnet 6 from the magnetic force. Here, the "low" speed means a case in which the centrifugal force applied to the self-compensating dynamic balancer by the spindle motor 9 is less than the magnetic force applied between the moving members 5 and the magnet 6.
The self-compensating dynamic balancer for a disk player having the above structure is coupled to the bottom of the turntable 1 and compensates for the internal vibrations due to the eccentric mass when the turntable 1 rotates at a speed beyond the natural frequency. Also, when the turntable 1 does not rotate or rotates at the low speed, the moving members 5 stick to the magnet 6 and do not generate internal noise. Further, when a disk player is installed vertically, the moving members 5 can easily overcome the pull of gravity.
However, in the self-compensating dynamic balancer for a disk player having the above structure, since a magnetic force is also generated between each of the moving members 5, a moving member for example 5a may stick to either a 5b or another neighboring moving member 5c, or to. Thus, the moving members 5 cannot be located at an accurate balancing position due to magnetic interference between the neighboring moving members, which results in inferior balancing performance.